Fancy a walk into London’s past? How about a stroll down Fleet Street in 1895? Or Oxford Street in 1899? It can be done. I can’t promise pictures, but I can offer more detail on the residents of each building than Google would risk publishing today.

The secret: from the mid-1830s, a man named Frederic Kelly employed agents to call at every address in London and to record the people or businesses within. Kelly was a postal official, and his agents, at least to begin with, were postmen. There was some scandal about that. Because this wasn’t an official census, conducted every ten years and then locked away for a century; this was a commercial operation, conducted annually and sold in a big fat book, the Post Office London Directory. It listed the names alphabetically, like a phone book today; classified by trade and profession, like a Yellow Pages; but also simply street by street. By the end of the 19th century, having absorbed many rivals, Kelly’s successors were doing the same thing for much of Britain, and they continued doing it well into the 20th century.

And then, about ten years ago, the National Lottery paid Leicester University to digitise a range of historical directories, and inadvertently created a vast internet time-sink that has swallowed much of my weekend. It’s the street-by-street listings that are the fascination. You get the contents of each building, street number by street number, but the positions of the junctions are also marked – ‘here is Tite st’, ‘here is Flood st & Cheyne wlk’ – which means that, with roads you know a little, it becomes shockingly easy to start visualising them as they were 100 or 150 years ago.

The ability to see a street change is also a big attraction. I’ve spent much of the past few days exploring successive versions of Wardour Street, in Soho, having been set on to the exercise by a stray phrase in this week’s Mind Your Language column. Tolkein, says Dot Wordsworth, ‘does not employ the “Wardour Street” fake antique that Fowler complained of in others: words like anent, trow, ween, whilom or wot‘. Now, I knew the standard explanation for why ‘Wardour Street English’ is meant to mean affected antiquity. It’s that Wardour Street was a centre of the antiques trade. But I’ve always been a bit suspicious of it: the insult was originally hurled at William Morris, who also made furniture, which caused me to wonder whether it might be a dig at his handiwork rather than at fake antiques in general; and then there’s not much trace of the antiques business on Wardour Street these days.

Thanks to historicaldirectories.org, I know exactly how wrong I was. To be a dig at Morris’s furniture, it would have needed to be ‘Queen Square English’: in the 1882 Kelly’s, Morris & Co. are listed as ‘fine art decorators’ at 26 Queen Square in Bloomsbury. And Wardour Street was a centre of the antiques trade before it had even fully settled on calling itself the antiques trade. The Wardour Street listing in the 1841 Kelly’s has two businesses styling themselves as antique furniture dealers among a rather greater number of ‘curiosity dealers’ and one guy, J. Hadnutt at number 40, who considered himself an ‘ancient furniture dealer’.

By 1882, no one is using the name ‘curiosity dealer’ but there are a hatful of antique furniture dealers, including a set of ‘antique furniture warehouses’ spread across three street numbers from 156 to 160. (There’s also a celebrity sighting: ‘Lear Edward, artist’ at number 129.) By 1915, however, that world had already disappeared: a couple of antique shops linger on, but the big emporium at 156 to 160 has become an electric lighting showroom and the most prominent residents are legion upon legion of movie companies, from Pathé to Paramount to Famous Players. So ‘Wardour Street English’ has itself been an obsolete term for nearly a century.

Another branch of the same rabbit hole: in 1900, Samuel Butler promised to replace Morris’s translation of the Odyssey – the one in ‘Wardour Street English’ – with one of his own, in ‘Tottenham Court Road English’. Plain but elegant modern prose, in other words, of the sort one might buy from Heal’s. Thanks to historicaldirectories.org, I know that Heal’s were on Tottenham Court Road in 1899 and the right sort of business for Butler’s joke to fit them: they’re listed as ‘upholsterers and cabinet makers’, having been ‘feather bed makers’ in the 1882 edition. But there are also a fair number of other cabinet makers on Tottenham Court Road, so it could be that it was simply the obvious place to buy new furniture, as Wardour Street was to buy old.

The Historical Directories site has directories from all over the country, with particular strengths in the 1850s, 1890s and 1910s, and it has full-text search, but the interface can be a bit frustrating: I had particular trouble with the map on the Find by location page. The easiest thing seems to be to head straight to the Find by keywords page, even if you aren’t planning on finding anything by keyword, and using the drop-down menus there to pick the sort of directory you want. From there, at least for the sort of free-form browsing I’ve enjoyed, you’re looking for volumes containing street directories, and the easiest way to get to the relevant bits is by using the ‘fact file’ links to the right of the search results.

As a starter kit, here are direct links to the fact file pages for the site’s five street directories of central London: 1841, 1882, 1895, 1899 and 1915. I’d be very interested to hear about your finds.

The only remaining thing is to thank the team who developed the site and, particularly, whoever in Leicester is keeping it online. The only item on the ‘news’ page is dated ‘January 2005′ and notes that the project’s funding ran out three months previously. It adds: ‘The site will remain freely available for 3 years.’ That was seven years ago. Let’s enjoy it while we can.

An initial search on a country village where my mother now lives and where many of my forebears also lived revealed several fascinating facts, additional to material I’ve previously discovered from the Censuses.

It is also a great testament to John Major’s original vision for the disbursement of funds raised for ‘good causes’; those projects and institutions that the State could never persuade Parliament and/or the electorate to fund yet, when delivered are quite obviously a great public benefit and resource.